Head restraint assemblies, which generally comprise a headrest component—commonly called a bun—adjustably supported on the top of a vehicle seat-back, protect a vehicle occupant from serious injury due to sudden acceleration or deceleration of the vehicle. In rear-seat applications, it is known for such head restraint assemblies to be selectively adjustable between an upright position, in which the head restraint assembly is generally vertically oriented relative to the seat back, and a folded position, in which the head restraint assembly is pivoted forwardly or rearwardly relative to the seat back and oriented approximately 90 degrees from the upright position. In the folded position, as is known, the seat is better configured for stowage (i.e., folding of the rear seat backs to convert the rear passenger area of the vehicle into a storage area). While many mechanisms are known for accomplishing pivotal movement of the head restraint assembly relative to the seat back, there is room for improvement.